The overall objective of this project is the synthesis of prostaglandin analogs in which the manyfold biological activities of the natural prostaglandins have been separated. This task is essential, since application of prostaglandins in medicine demands that the desired activity be accompanied by a minimum of "side effects". Goals for the current year are: A) Completion of the Synthesis of 10,10-Difluoroprostaglandins. B) Further Studies of the Synthesis of Dithia Analog of the Prostaglandin Endoperoxide. C) Completion of the Synthesis of 8, 12-Seco Prostaglandins. D) Investigation of Alternatives and Modified Routes to 13-Dehydroprostaglandins. E) Investigation of Routes Leading to the Thromboxanes. BIBLIOGRAPHIC REFERENCES: W. S. Powell, S. Hammarstrom, B. Samuelsson, W. L. Miller, F. S. Sun, J. Fried, C. H. Lin and J. Jarabak, Interactions between prostaglandin analogs and a receptor in bovine corpora lutea. Correlations of dissociation constants with luteolytic potencies in hamsters. Eur. J. Biochemistry, 59, 271 (1975). J. Fried, M. S. Lee, B. Gaede, J. C. Sih, Y. Yoshikawa and J. A. McCracken, Chemical and Biological studies on 13-Dehydroprostaglandins, in "Advances in Prostaglandin and Thromboxane Research, Vol. 1, Raven Press, New York, N. Y., 1976, p. 183.